In recent years, requirements for a low fuel consumption of automobiles are becoming severer in connection with the movement of global emission control of carbon dioxide which follows social requirement for energy saving and a rise in concern about environmental problems. In order to meet the above requirements, tires which are reduced in rolling resistance and have low heat build-up as tire performances have come to be demanded. In respect to a method for reducing rolling resistance of a tire, it is carried out as the most usual method to use a material exhibiting lower heat build-up as a rubber composition.
Many technologies such as addition of loss reducing agents, improvement in dispersibility of carbon black added as a filler for reinforcement by modification of polymers and use of silica for a filler have so far been studied as techniques for reducing heat generation of rubbers.
A lot of modified rubbers interacting with fillers such as carbon black and silica have so far been developed as a method for improving rubber components (patent document 1), but a satisfactory modifying effect in rubber compositions compounded with carbon black and silica is not necessarily obtained. Also, liquid styrene-butadiene rubbers having a low molecular weight are used in order to improve abrasion resistance (patent documents 2 and 3). Further, a technology for improving a storage modulus includes compounding of polyethylene glycol polymaleate (PEGM) (patent document 4).